Medical thermometers are typically employed to facilitate the prevention, diagnosis and treatment of diseases, body ailments, etc. for humans and other animals, as is known. Doctors, nurses, parents, care providers, etc. use thermometers to measure a subject's body temperature for detecting a fever, monitoring the subject's body temperature, etc. An accurate reading of a subject's body temperature is needed for effective use and should be taken from the internal or core temperature of a subject's body. Several thermometer devices are known for measuring a subject's body temperature, such as, for example, glass, electronic, ear (tympanic).
Glass thermometers, however, are very slow in making measurements, typically taking several minutes to determine body temperature. This can result in discomfort to the subject, and may be very troublesome when taking the temperature of a small child or an invalid. Further, glass thermometers are susceptible to error and are typically accurate only to within a degree.
Electronic thermometers have shorter measurement times and improve accuracy over glass thermometers. Electronic thermometers, however, still typically take about thirty (30) seconds to get an accurate reading. They can also cause discomfort as the thermometer device must be inserted into the subject's mouth, rectum or axilla.
Tympanic thermometers are generally considered by the medical community to be superior for taking a subject's temperature. Tympanic thermometers provide rapid and accurate readings of core temperature, overcoming the disadvantages associated with other types of thermometers. Tympanic thermometers measure temperature by sensing infrared emissions from the tympanic membrane (eardrum) in the external ear canal. The temperature of the tympanic membrane accurately represents the body's core temperature. Further, it only takes a few seconds to measure a subject's temperature in this manner.
In operation, a tympanic thermometer is prepared for use and a probe cover is mounted onto a sensing probe extending from a distal portion of the thermometer. The probe cover provides a sanitary barrier between the subject and the thermometer. A practitioner or other care provider inserts a portion of the probe having the probe cover mounted thereon into a subject's outer ear canal to sense the infrared emissions from the tympanic membrane. The infrared light emitted from the tympanic membrane passes through a window of the probe cover and is directed to the sensing probe by a waveguide. The essential feature of the window is that it is substantially transparent to infrared radiation, thereby allowing infrared radiation from the tympanic membrane to pass through the probe cover to the heat sensing probe of the thermometer. Although an open window would be suitable for taking a temperature measurement, a film (e.g., a plastic film) having a thickness on the order of the wavelength of radiation in the far infrared range typically spans the window to provide a sanitary barrier.
The practitioner presses a button or similar device to cause the thermometer to take a temperature measurement. The microelectronics process electrical signals from the heat sensor to determine eardrum temperature and render a temperature measurement in a few seconds or less. The probe is removed from the ear canal and the probe cover discarded. A new probe cover is used each time the thermometer is used with a new subject.
Known tympanic thermometers typically include a probe containing a heat sensor such as a thermopile, a pyroelectric heat sensor, etc. See, for example, U.S. Pat. Nos. 6,179,785, 6,186,959, and 5,820,264. These types of heat sensors are particularly sensitive to the eardrum's radiant heat energy. The accuracy with which the sensing probe senses the infrared radiation emitted by the eardrum directly corresponds with the overall accuracy, repeatability and usability of the tympanic thermometer. The sensing probe must be sensitive to the low level of infrared energy emitted by an eardrum while providing a high degree of accuracy, repeatability and thermal noise immunity.
Current tympanic thermometers employ probe covers that may adversely affect accuracy of a temperature reading. The probe cover window of the probe cover typically contacts the probe. Consequently, the distal end of the probe can become disadvantageously heated by conductive heat transfer from the window, which is heated by its proximity to the subject. This may cause the sensing probe to detect radiation emitted from the heated distal end of the probe or other undesirable sources causing thermal noise that can lead to inaccurate temperature measurement. Further, current probe cover designs suffer from other drawbacks, such as poor retention characteristics with the probe and subject discomfort when inserted in the ear canal. In addition, the window through which the infrared radiation passes may be distorted during the measurement process. Such distortions may be caused by manufacturing inconsistencies and/or by deformation of the probe cover upon insertion of the probe into the cover or by insertion of the probe into the ear canal.
Therefore, it would be desirable to overcome the disadvantages and drawbacks of the prior art with a probe cover for a tympanic thermometer that improves accuracy and reliability of temperature measurements, for example by reducing conductive heat transfer to the probe and/or reducing error from distortions in the film barrier covering the window. It would also be desirable for such a probe cover to be comfortable for the subject. Further, it would be highly desirable if the probe cover was designed to facilitate stacking (e.g., nesting) of multiple probe covers for convenience in storage.